1. Field of invention
This invention involves an apparatus and method for removing a ball staked head gimbal from a head stack assembly.
2. Description of Related Art
In computer disk drives, magnetic heads for reading rotating magnetic disks are mounted on relatively delicate structures known as "head gimbals". A plurality of head gimbals are typically firmly mounted on a structure known as a "head stack assembly". A common type of head stack assembly is an "E" block, which refers to the general shape of the head assembly. FIG. 1 depicts a typical "E" block head stack assembly 1 and a number of attached head gimbals 2. Each head gimbal 2 includes a staking plate 2a and a flexure 2b. A disk read/write head 3 is affixed to the end of each flexure 2b. These disk heads 3 read data from, or write data to, the rotating computer disk 4.
A hollow, cylindrical staking hub 5 extends from the lower surface of each staking plate 2a. A corresponding staking hole 6 is located in each arm of the "E" block 1. The staking hub 5 of a head gimbal fits into the staking hole 6 located in the arm of an "E" block. A staking tool is then inserted into the hole of the staking hub and the hub is expanded to create a very tight friction fit against the sides of the staking hole 6. Generally, head stack assemblies contain four to sixteen head gimbals which are staked, or swaged, in line and spaced approximately 0.150 to 0.200 inches apart.
In order to replace a defective head gimbal from any position in a head stack assembly, a removal tool must be used. Prior methods include a series of tools which force rotation of the head gimbal to approximately 45.degree. from its true position. Once the gimbal is rotated, the corners of the gimbal are exposed and can be pried upward or downward to remove the gimbal from the stack assembly. This method of removal creates considerable stress on the stack assembly 1 and can distort the staking hole 6. Using this method of removing head gimbals, rework can typically only be done twice in any one position due to the damage caused by the removal procedure.
Therefore, it is an object of this invention to provide an apparatus and method for removing a ball staked head gimbal while minimizing damage to the head stack assembly.